1. Field of the Invention
This invention relates generally to the field of combustion turbines and the art of fabricating and assembling combustion turbine systems. More specifically, this invention relates to an improved method and apparatus for aligning adjacent cylinders in a combustion turbine that is far more efficient than conventional processes are.
2. Description of the Prior Art
Combustion turbines such as those manufactured by the owner of this invention, Westinghouse Electric Company, typically include several cylinders that need to be precisely aligned in order to insure that there is no rubbing during operation between the rotating and stationary components. In at least one common model of combustion turbine, the cylinders need to be aligned within approximately 0.015" from centerline to centerline.
Conventionally, the cylinders are aligned by loosening the vertical joint bolting that secures one cylinder to another, and using mechanical jacks between the floor and the respective cylinders or an adjacent unit to adjust the vertical and horizontal positions of each cylinder. The alignment is then checked by measuring the distances between selected locations on each cylinder and a wire that is stretched through the engine and centered to the bearing bores on each end.
Unfortunately, due to the weight and geometry of the cylinders it is very hard to determine the exact amount of movement that is obtained by jacking at one point on the cylinders. The cylinders do not stay round during the jacking process, so the bottom might move significantly more than the top during jacking. This creates a situation where alignment readings cannot be reliably repeated, and the alignment process must typically be performed between 4 and 7 times to obtain the necessary tolerances. As a result, the alignment process is expensive and time consuming; it can take several days.
It is clear that a long and unfilled need exists for an improved method and apparatus for centering the cylinders in a combustion turbine that is less time consuming and more efficient than convention techniques are.